As the complexity of technical systems increases, the interaction of operators with these systems increasingly comes into focus. One important aspect is the measurement of facial parameters such as the head pose, the eye gaze direction, eyelid closure and facial expressions. Improvements in computer vision and the availability of cheap computing power allow for consumer grade systems to measure these facial parameters.
An example eye gaze detection system is that proposed in Patent Cooperation Treaty Application Number PCT/AUO1/00249 entitled “Facial Image Processing System” and PCT/AU2004/000413 entitled “Eye tracking system and method” assigned to the assignee of the present application the content of which are hereby incorporated by cross reference.
Typically, in such facial parameter measurement systems, an image sensor is utilised, focused on the operator and deriving the required information from the image sequence in real time. The ability to measure these facial parameters has numerous applications, with many new applications continuously being created.
In some areas such as human-machine interface (HMI) design, it is highly desirable to measure the interaction of operators with the system in order to optimise the design of the system itself. One example is the design of car cockpits and auxiliary devices such as navigation systems. Here it is of utmost importance that the increasing amount of information provided to the driver by the systems does not distract the driver from the primary tracking task. Developers often measure how often and for how long users glance at the control panels in order to obtain a certain piece of information or perform a certain task. This data is then used to optimise the layout of the HMI.
In other systems, the measurement of the facial parameters of the user can be part of the operation of the system itself. For example, in automotive driver assistance systems that derive fatigue and distraction information from facial parameters. Other domains where fatigue is of interest include the operation of technical systems such as flight controllers, military mission control, plant control, heavy equipment control in mining or oil exploration and in other modes of transport such as marine and aviation.
Head and gaze tracking systems are also employed today as personal computer input devices for disabled people. As interfaces to personal computers evolve, head and gaze tracking may become as ubiquitous as computer keyboards and mice. Already systems are available that let users control the face of computer avatars in computer games and chat rooms using a head and eye tracking system.
Head and face tracking also has strong applications in biometric face recognition systems. The localisation and identification of a camera view suitable for recognition are basic capabilities of face recognition systems and are particularly important when the person to be recognised is not cooperating with the system as is the case in typical “face in the crowd” applications.
Systems for accurate face tracking often face particular difficulties where the user is wearing glasses and can fail to operate properly.